Photoactive semiconductor nanocrystals are of interest for numerous optical and electronic applications. Semiconductor nanocrystals frequently include a semiconductor core and a passivating, semiconductor shell. Shell materials with bandgaps higher than those of the core materials can minimize deep-trap emission sites and can enhance quantum yield and stability of the nanocrystal particle. The optical properties and stability of a fluorescent nanocrystal can be compromised when in contact with metal atoms. In the presence of metals (e.g., metal ions or metal substrates), the intensity of fluorescence emission intensity of the semiconductor nanocrystals can be dramatically reduced. Once quenched, it is often impossible to regenerate the fluorescence emission of the nanocrystal. This sensitivity to metals severely limits the use of semiconductor nanocrystals in applications requiring contact with metal ions or metals (e.g., catalysts and metal substrates). Thus, there is a need to develop materials and methods for restoring the fluorescence intensity of quenched nanocrystals.